With regard to conventional alternative compressor assemblies
It is already known from those skilled in the art that alternative compressors comprise machines and/or devices capable of altering the pressure of a working fluid as well as pumping it. In this sense, and in a more specific form, alternative compressors are capable of altering the pressure of a working fluid by controllably altering the volume of a compression chamber that is usually defined by a cylindrical chamber that is able to receive the working fluid and a movable piston. Therefore, due to the displacement of the movable piston occurring inside the compression chamber the volume thereof is alternatively (decreased and increased) altered.
Additionally, it is also known from those skilled in the art that the inlet (suction) and removal (exhaustion) steps of the working fluid inside the compression chamber consist of critical steps to achieve a current functioning of an alternative compressor. Furthermore, said steps directly impact the parameters of a compressor performance, and, for this reason, the current state of the art comprises a great number of valve systems intended to control suction and discharge of working fluid inside the compression chamber.
In accordance with the conventional functioning of a state-of-the-art valve system, it is observed that conventional suction valves have a normal closed configuration, and their automatic and uncommanded “opening” uniquely and exclusively occurs when the piston is at the superior dead point and descends to the lower dead point, that is, the current suction valves can only be kept “open” when the pressure inside the cylinder drops to a value that is lower than the pressure in the suction chamber.
Such an operability of the current suction valves, although functional, can be further improved since as it can be observed it is necessary to generate a favorable pressure difference such that they can “open” and in this connection, in addition to a higher starting force for the electric motor that moves the piston, a greater energy loss for pumping the fluid is required. Conventional solutions provide for an oversizing of this motor (to allow for it to “start” the compressor), ou also the use of complex and expensive specific starting systems.
Concerning conventional discharge valves, they also have a normal-closed configuration, and their automatic and uncommanded “opening” uniquely and exclusively occurs when the piston travels from the lower dead point and goes towards the superior dead point, thereby increasing the pressure inside the cylinder, i.e. when the pressure inside the cylinder is higher than the pressure in the discharge chamber.
Such operability of the current charge valves although also functional prevents any sort of capacity modulation of the compressor in conjunction with the maintenance of the motor speed.
With regard to the current alternatives of capacity modulation of compressors
According to the widely spread state-of-the-art understanding, it is known that only compressors with variable speed are able to change an operation speed, thereby modulating the capacity thereof while the so-called ON-OFF computers do not have this advantage.
In the case of the cited compressors with variable speed, which are based on continuous current (VCC) electrical motors, it can be observed that as the compressor reduces its operation speed the lower is the gas mass displaced into any system (such as, for example, refrigeration systems), and, consequently, elevated gains of effectiveness increase in systems demanding varying gas masses can be obtained.
Current compressors with varying speed use a complex electronics in association with a permanent-magnet motor, and, generally, this association of magnets with electronics has high costs. Another limitation of such compressors refer to a minimum speed at which it can operate since this minimal rotation value is also directly connected with the compressor reliability.
Further, as a palliative alternative to the capacity modulation of compressors, the current state of the art provides certain solutions where suction and/or discharge orifices of a valve plate can have their diameter relatively altered (partially obstructed) during their respective functional step.
U.S. Pat. No. 3,844,686 and US Patent Application 2010/004387 disclose, for example, electromagnetic mechanisms capable of directly or indirectly promoting decrease/increase in the suction and/or discharge diameter; nevertheless, such mechanisms only have relevant operability when suction or discharge valves are operationally “opened.”
Based on the above explained context, it can be clearly noted that the current state of the art concerning valve systems of alternative compressors essentially relies on non-flexible and non-customizable equivalent operational principles.
Furthermore, it is also noted that the current state of the art relative to means for modulating the capacity of alternative compressors refers to not entirely applicable solutions, or also to expensive solutions which are not applied to more ordinary applications.
Based on this scenario the present patent of invention was developed.